package hadoop;

import java.io.IOException;
import java.util.StringTokenizer;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;

public class WordCount{
	public static class Map extends Mapper<LongWritable,Text,Text,IntWritable>{
		private final static IntWritable one = new IntWritable(1);
		private Text word = new Text();
		
		public void map(LongWritable key,Text value, Context context) throws IOException, InterruptedException{
			String line = value.toString();
			StringTokenizer tokensizer = new StringTokenizer(line);
			while(tokensizer.hasMoreTokens()){
				word.set(tokensizer.nextToken());
				context.write(word, one);
			}
		}
	}

	
	public static class Reduce extends Reducer<Text,IntWritable,Text,IntWritable>{
		public void reduce(Text key,Iterable<IntWritable> values,Context context) throws IOException, InterruptedException{
			int sum = 0;
			for(IntWritable val : values){
				sum += val.get();
			}
			context.write(key, new IntWritable(sum));
		}
	}
	
	
	public static void main(String[] args) throws Exception{
		Configuration conf = new Configuration();
		Job job = new Job(conf,"word count");
		job.setJarByClass(WordCount.class);
		
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(IntWritable.class);
		
		job.setMapperClass(Map.class);
		job.setReducerClass(Reduce.class);
		
		job.setInputFormatClass(TextInputFormat.class);
		job.setOutputFormatClass(TextOutputFormat.class);
		
		FileInputFormat.addInputPath(job,new Path(args[0]));
		FileOutputFormat.setOutputPath(job, new Path(args[1]));
		
		job.waitForCompletion(true);
		
		//System.out.println("hello world");
	}
}
